Crystal-field effects on the transport properties of rare-earth intermetallics

Low-temperature (1.5-11 K) measurements on the electrical resistivity and thermal conductivity of the pnictide compounds $L\mathrm{Sb}$ ($L=\mathrm{E}\mathrm{r},\mathrm{T}\mathrm{m},\mathrm{L}\mathrm{a}$) and the rare-earth intermetallic compounds (Pr${\mathrm{Cu}}_5$, Pr${\mathrm{Pt}}_5$, La${\mathrm{Pt}}_5$) are reported. The anomalous temperature dependence of these transport coefficients suggests strong evidence of an increased scattering of the carriers through exchange and aspherical Coulomb interaction with the localized $4f$ electrons. Results are compared with theory and good quantitative agreement is obtained. Values of the parameter $r_i$, which measures the strength of the exchange and the aspherical Coulomb interaction arising from different thermally populated crystal-electric-field states, were also obtained.